Ship stabilizing apparatus



Sept. 29, 1959 F..M. M. B. SALOMON 25906330 SHIP STABILIZING APPARATUS Filed Jan. 29, ls? 4 sheets-sheet 1 Sept. 29, 1959 F. M.4M. B. SALOMONv 2,906,230 A SHIP STABIILIZING APPARATUS 4 Sheets-Sheet 2 Filed Jan. 29, 1957 /D////////////./////// /fw 1 1 1 l 1 /4 rl F. M. M. B. SALOMON SHIP STABILIZING APPARATUS Sept. 29, 1959 Filed Jan. 29, 1957 4 Sheets-Sheet 3 En u1 Sept. 29, 1959 9 F. M. M.'B. sALoMoN 2,906,230

SHIP STABILIZING APPARATUS Filed Jan. 29, 1957 4 Sheets-Sheet 4 I 63 26 8a 1 6o o 64 a N 5a 1 j l/ 5 ,ff Flg. 5

lWL/f/Wof United States Patent SHIP STABILIZING APPARATUS Franois Marie Michel Bernard Salomon, Paris, France Applicants January 29, 1957, serial No. 636,992

Claims priority, application France February 1, 1956 10 claims. (cl. 114-125) The present invention relates to an apparatus intended to apply Aalternating mechanical impulses to a frame.

This apparatus is more particularly but not exclusively intended to prevent rolling of ships. It may also serve to prevent other kinds of oscillations than the rolling of ships.

The invention, in the case in which it is applied to reduce or to damp-out the rolling oscillation of a ship, relates especially to the utilization of the movements and of `the changes in direction of a liquid mass working in a closed circuit under the following conditions:

(l) At least one driving mechanism maintains a continuous movement of a liquid mass and imparts thereto a generally rapid movement in a given direction, about an ,axis parallel to the axis of rolling of the ship;

(2) At chosen moments, and preferably under the action of controlling mechanisms, at least one part ofv thisliquid mass is forced to pass through reaction members which are fixed with respect to the hull of the ship and are arranged so as to force the streams of liquid to change direction whilst maintaining substantially constant the vis viva of the liquid.

The streams of liquid during their passage through the said reaction members, apply to these members a couple which is transmitted to the hull and which represents the useful vanti-rolling couple.

(3) The liquid continuing its movement, passes, without losing its vis viva (except for slight losses) into a second rotation maintaining member similar to the first and having its axis preferably parallel to that of the first maintaining member, and in which the linear speeds are substantially equal in absolute value to the speeds which it possessed in the first rotation maintaining member, but in the opposite direction.

(4) At chosen moments, and preferably under the` action of servo-control mechanisms, the liquid is forced to pass into further reaction members which are rigidly fixed to the hull and which force the streams of liquid to change direction a second time, whilst Ymaintaining substantially constant the vis viva of the liquid.

In this second change of direction, the streams of liquid apply tothe reaction members a couple of opposite sense to that which was previously applied, and which is transmitted to the hull. t

(5) The liquid immediately returns, without loss of vis viva (except for small losses) into the first driving member in which it again assumes, after the two changes in direction to which it has been subjected in the reaction members, the movement which it had previously.

The same cycle of operations take place, Vpreferably under the action of servo-control members, under conditions which will be explained later. t

It is the same liquid mass which is concerned during theA course of the successive cycles,and,since thevis viva is maintained constant (except for very small losses), the power required for the movement of the ,rnaintaining members is reduced to a minimum. (The motors con- Patented Sept. 29, 1959 ICC cef-ned with the maintenance ,of the movements compensate moreover for the small losses which are inevitable.

As will be explained in detail later, the movements of the liquid under the action of kservo-control mechanisms which will be described below, are regulated in such manner as to obtain the following results:

The vector M representing the kinetic moment of the total mass of liquid with respect to an axis coupled to the ship and parallel to its rolling axis:

(a) At each instant t, the speed ofthe extremity of the vector M changed in direction is substantially equipollent to the couple which must be applied to the hull of the ship in order to oppose, at that instant, the rolling movement, in the best conditions.

(b) The vis viva of the liquid usedwhich operates I in a closed circuit-remains at the same time preferably substantially constant, so that it may not be necessary (with the exception of small losses) continually to reconstitute this vis viva.

In certain forms of embodiment of the invention, the

liquid is driven in the movement of rotation of a first` casing which turns around an axis parallel to the rolling axis, and is drawn from this casing by extraction members.

The liquid then passes into piping systems which are.4

` in which it substantially retains its speed, and in which it continues to rotate with this casing until the couple which it is necessary to apply to the hull to counteract the rolling, has changed in direction. A second extracA tion (or drawing) system then takes the liquid from the second rotating casing and passes it into piping systems rigidly fixed to the hull, in which it applies a useful couple of opposite direction tothe preceding couple and brings it back by means of'injection members into the first rotating casing, again substantially maintaining its speed. (The maintenance of this speed is important from the point of View of economy of energy.)

A particularly interesting case is that in which the second lcasing rotates in the opposite direction to the first casing, about an axis parallel to that of the first or which may even be geometrically coincident with that of the first.

In the liquid circuit indicated above, the total vis viva of the liquid has remained substantially constant, with the exception of small losses (which are moreover compensated by the driving motors of the rotating casings),

but its kinetic moment has varied and it is the variations of this kinetic moment which have applied to the ship, through the intermediary of the piping systems fixed to the hull, the useful couples which counteract rolling.

The movements and ,the discharges of the extraction members and the injection members are determined by a servo-control system which executes the orders transmitted to it by an automatic calculating apparatus, of known type.

This automatic calculating apparatus is coupled, in known manner, to various measuring or detection devices which measure the various factors concerned in the phenomenon of rolling. In order to measure these factors, use may be made in known manner of apparatus, which enable'the various parameters to be determined which depend yfrom the inclination of the ship, and especiallyrthe pendulums, small gyroscopes (sometimes known as gyropilots), accelerometers, etc.

Devices may also be employed which are sensitive to the pressure of the sea on the ship, for example pressure gauges of various types, piezoelectric devices, ete.

Finally, with a view to counteracting rolling, the detectors are rst of all concerned. Their indications are transmitted in known manner to a calculator which gives the necessary function or functions or the useful factors. The calculator controls the extraction devices and the injection devices of the liquid by means of servo-control mechanisms.

The equipments in accordance with the invention differ considerably from anti-rolling apparatus of known types, and have in particular the following advantages:

(1) The mass of liquid employed is small.

(2) The construction is simple and is particularly simpler than that of gyroscope damping devices, which have especially the serious drawback that they necessitate bearings which are subjected at the same time to high speeds of rotation and to enormous stresses. These drawbacks do not exist in the apparatus in accordance with the invention, in which in particular, the bearings of the rotating casings may be subjected to high speeds, but they are required to withstand much lower stresses and they are especially not subjected to the anti-rolling forces which are applied to the xed piping systems which have been refererred to above.

(3) They are less bulky and lighter than thetanktype anti-rolling dampers, which require large masses of liquid and large tanks.

(4) They consume much less energy than anti-rolling devices which employ pumps.

(5) They do not necessitate considerable modifications to the hull which are inevitable with many other systems, especially with rolling dampers with paddles or rudder members.

(6) They are capable of obeying almost instantaneously.

(7) They can readily be made by mass-production methods.

A number of further special features of the invention will become apparent from the description which follows below with reference to the accompanying drawings, which are given in order to facilitate understanding of the invention and, by way of example, without implied limitation. The drawings relate by way of example to antirolling equipment for ships, but it is of course understood that very different forms may be employed without thereby departing from the spirit or from the scope of the mvention.

In these drawings:

Fig. 1 is a cross-section through a vertical plane passing through the axis of rotation of an apparatus in which the two rotating casings are coaxial and end to end, rotating in opposite directions.

Fig. 2 is a cross-section taken through the plane A--A of Fig. 1.

Fig. 3 is a cross-section taken through the plane B-B of Fig. 1.

Fig. 4 relates to an apparatus similar to that of Fig. 1, but in which one of the rotating casings is mounted inside the other.

Fig. 5 is a fragmentary perspective view showing diagrammatically the apparatus of the present invention mounted in the hull of a ship.

In Fig. l, a motor drives in rotation a shaft 2 carried by a bearing 3. This bearing 3 is fixed to the deck 4 of the ship by the support 5, and the motor 1 is xed on a bracket 6 rigidly fixed to the support 5.

The shaft 2, which is parallel to the longitudinal axis of the ship rotatably drives a rotary casing 7 having an external rim 8. This casing is closed by an end plate 9Vwhich is rigidly xed to a sleeve 10. This sleeve 10 is supported on the counter-bearing 11 rigidly fixed to the frame 12, and its axis is an extension of the axis of the shaft 2. The frame 12 is fixed to the deck 4 of the ship.

The casing 7 is provided with paddles 13 and 14 and rotatably drives without sliding (or substantially without sliding) a certain portion L1 of a liquid L. Under the action of centrifugal forces produced by the rotation of the casing 7, the internal surface of the liquid takes the form of a cylinder of revolution having generators xlyl and x'ly'l.

As shown on the right-hand side of Fig. l, the apparatus comprises a further device entirely similar to that which has just been described.

A motor 1a rotatably drives a shaft 2a carried by a bearing 3a. The bearing 3a is fixed to the deck 4 by means of the support 5a, and the motor 1a is mounted on a bracket 6a integral with the support 5a.

The shaft 2a is also parallel to the longitudinal axis of the ship and, in the case shown in Fig. 1, its axis is an extension of the axis of the shaft 2. It drives in rotation a rotary casing 7a having an external rim 8a and it is closed by an added end-plate 9a which is rigidly xed to a sleeve 10a. The sleeve 10a is carried by the counterbear ing 11a rigidly xed to the frame 12, and its axis is the same as that of the sleeve 10 and of the shafts 2 and 2a.

The casing 7a carries paddles 13a and 14a and drives in rotation without sliding (or substantially without sliding) a further part L2 ofthe liquid L, the internal surface of which is a cylinder of revolution having generating lines xzyz and x2y2.

In the apparatus shown in Figs. 1, 2 and 3, the rotary casings 7 and 7a are driven in rotation in opposite directions to each other (in accordance with the arrows F1 and F2 drawn on Figs. 2 and 3) and preferably at equal speeds in absolute value and, consequently, the portions L1 and L2 of the liquid L rotate in opposite directions from each other, but preferably at equal linear speeds in absolute value.

There will now be described the reaction devices coupled to the frame of the apparatus (and consequently to the ship) and which force a part of the liquid to pass from the rotary casing 7 into the rotary casing 7a and viceversa.

In Fig. l, there can moreover be seen only the two devices which enable the liquid to be drawn from the rotary casing 7 in order to cause it to pass into the rotary casing 7a (and not those which pass the liquid from the casing 7a to the casing 7).

These two devices are identical and can be deducted one from the other by a rotation of 1r about the general axis of rotation. One of these devices will now be described.

This comprises essentially a fixed piping system formed in the frame Vof the apparatus and having its two extremities arranged, one to draw-olf the liquid (extraction device), the other to send it back (injection device). This piping system is formed by two tubes 15 and 16 rigidly fixed to the frame and coupled to each other by a channel 17 housed in the frame.

Over the tube 15 is adapted to slide a tube or draining member 18 which terminates in a curved-back and attened portion 19forming a scoop (Figs. 1 and 2) and which is intended to extract the liquid from the rotary casing 7. Around the sliding tube 18 is provided a further tube 20 rigidly fixed to the frame so as to form between the tube 18 and the tube 20 chambers 21 and 22 which are further defined by the piston 23 fixed to the tube18, the cover 24 and the bottom 2S, and are intended to regulate the displacement of the tube 18 by hydraulic means.

To this end, the chambers 21 and 22 are connected by meansof conduits21 and 22 (shown in Fig. 2) housed in the `frame-,ato a control box shown diagrammatically at 26-in Fig. 1. 'By means'of this box 26 and the conduits 21 and 22A,'it is possible. to put under pressure, either the liquid contained in the chamber 21 or the liquid Contained in the chamber 2,2, which .enabls ithe piston 23 and the tube 18 which is fixed to it to be moved in the desired direction.

On the tube 16 is arranged to slide a tube or conduit 27 which terminates in a curved-back portion 28 forming an injector (see Figs. 1 and 3) and which is intended to send the liquid into the rotary casing 7a. The tube or conduit 27 may be displaced laterally by hydraulic means similar to those which have just been described in respect to the movement of the tube or draining member 18.

The scoops may be displaced between the two following extreme positions: complete immersion in the liquid and completely clear of the liquid. In order to permit complete penetration into the liquid so as to extract it completely, channels 29 and 29a are provided in the rims 8 and 8a so as to co-operate with the extremities of the Scoops. On the other hand, ribs 30 and 30a are provided round the rims 8 and 8a in order to increase their strength.

As has already been previously stated above, there can be seen in Figs. 1, 2 and 3, a second device arranged at 180 to the iirst and intended also to extract the liquid from `the casing 7 in order to send it into the casing 7a. This device is identical with that which has just been described.

The internal shape of the scoops is sol arranged that the liquid passes into them tangentially or `substantially tangentially in order to avoid losses of energy. The external shape of the scoop is arranged so as to avoid parasitic phenomena and turbulence.

The penetration of a scoop into the liquid is effected very gradually as and when the quantity of liquid in the casing diminishes, and generally in such manner that the mouth of the scoop may be almost whollyvplunged into the liquid, but with the lower edge of the mouth t tangential or almost tangential to the internal surface of the liquid.

The two scoops which are located in the same rotary casing, for example the two scoops shown in Figs. y1 and 2 inthe casing 7, have in general symmetrical displacements in order to maintain a perfect balance.

The internal shape of the injection nozzles is determined in such manner that the liquid ris discharged therefrom as tangentially as possible to the internal surface of the liquid which Aalready exists inside the casing, and that the streams of liquid may be free from turbulence.

The displacement of the injection nozzle Vis elected gradually Yfrom the periphery and in accordance with the passage of the liquid into the casing.

All the surfaces of the piping systems, the scoops and the injectors which are in contact with the liquid are made as smooth as possible.

There will now be described the two devices which enable the liquid to be extracted from the casing 7a so as to return it to the casing 7.

These are only shown in Figs. 2 and 3. They are identical with each other and, like those previously described, may be deduced one from the other by a rotation of 1r about the general axis of rotation. They are furthermore identical to the devices described above with the exception that the scoop-carrier tubes are now in the casing 7a (that is to say shown in Fig. 3, which is the cross-section of the casing 7a) whilst the injector-carrier tubes yare in the casing 7 and are shown in Fig. 2 which is the cross-section of the casing 7. Each of these devices-comprises a vtube 31 (see Fig. 3) rigidly fixed to the frame, and a tube 32 (see Fig. 2) also fixed to the frame, these two tubes being coupled together by a piping system 33 (see Figs. 2 and 3) also housed in the frame and identical with the piping -system 17 of Fig. l.

,0n the tube 31 (Fig. 3) is arranged to slide a tube 34 which terminates in a curved-back and flattened portion `3S forming a scoop, intended to extract the liquid from t6 the rotary casing 7.a. On thev tube 32 (Fig. I2) is adapted to slide a tube 36 which terminates fn, acurved-back portion 37 forming an injector intended to Sendback, the liquid into the casing 7. v

The displacements of the tubes 34 and 36 are elected hydraulically in the same manner as the displacementsv of the tubes 18 and 27, and this under conditions which will be explained later. v

In a very general way, the control of the extraction and injection devices may be effected by very varied kinds of hydraulic means, or also by mechanical or electrical or pneumatic means, orby various combinations of these means.

In the positions shown in Figs. 1, 2 and 3, the -two scoops 19 (see particularly Fig. 2) are plunged-into v.the

ring of liquid driven in rotation by the casing 7.`

On the other hand, the injectors 37 (see Fig. 2) .are in the withdrawn position. The result is that the positions shown correspond to an instant when the liquid driven by the casing 7 in the direction of the arrow F1 is extracted from this casing.

At the same time, the injectors 28 (see Figs. l and 3) are in a tangential position to the liquid ring of the casing 7a and inject the liquid into this casing in the direction of rotation of the casing (arrow F2). As regards the scoops 35, these are then in the withdrawn position in the casing 7a.

The operation takes place 4as follows:

At every instant t, the liquid ring whch is driven in rotation at an angular speed u1 by the casing 7 possesses, with relation to the axis of rotation, a kinetic moment l, represented by a vector parallel to the axisv of rotation,l which axis is in addition parallel to the rolling axis of the ship. r Moreover, the value of this kinetic moment` (or moment of the momentum of the liquid) is:

IZ1=WZ1R12H1 in which m1 is the mass of this liquid ring in the casing 7, R1 is its radius of gyration, and u1 its angular speed.

At the same instant, the liquid ring inside the casing 7a is driven by this casing at an angular speed of .zzl, and its kinetic moment relative to the axis of rotation is similarly: v

` M 2=-m2R22u1 in which m2 is the mass of this liquid ring and VR is its radius of gyration.

The total kinetic couple is given by the albebrac equation:

the couple applied at each instant on the hull is equal to the differential: j

dM d "ZZT l In order to vary the factor m'1R13.-m2R22, it is only necessary to send liquid from the casing 7 to the casing 7a or vice versa. In other words, it is necessary to transfer the liquid from the casing 7 to the casing 7a, or viceversa, depending on the instants. f Y

In addition, this transfer should be made more or less quickly, depending on the cases and the instants, in order to give the ditlerential expressed above the appropriate value at each instant t. During the course of this trans- `fer, the liquid applies to the reaction members formed by the conduits,r the useful anti-rolling couples.

As has been previously stated, the transfer' members are controlled at every instant by a control box 26, which, in the case of Figs. l, 2 and 3, acts by hydraulic means on the scoop-carrier tubes and `on the 'injection tubes in order to extract at Yeach `instant inthe Ydesired direction (that is to say from left to right or from right to left, depending on the instants) and with a `desired ratel of ow.

' The box'26 comprises for example an assembly of servo-motors (not shown) which are generally electric motors driving pumps. It is these pumps which control hydraulically the pistons such as the pistons 23 of the extraction devices (see Fig. l) and also the corresponding pistons of the injection devices.

The servo-'motors are controlled in dependence on an automatic calculating apparatus which produces the necessary function or functions of the parameters which are transmitted to it by the various detection devices.

These detection devices themselves measure, at each instant, the various factors which are involved in the phenomenon of rolling. These are in particular the various parameters which are in relation with the inclination of the ship and especially the angle of roll, and their variations with time (differentials, integrals, etc.). They are also the various parameters which are associated with the pressure applied by the sea to the hull.

As regards the measuring or detection devices, there may be employed in particular, small pendulums, small gyroscopes (gyro-pilots) accelerometers, pressure gauges of varioustypes and especially piezo-electric devices.

One of the advantages of the invention is the possibility of varying certain characteristics of the apparatus in accordance with the circumstances and the times. Depending on the amount of swell, it is possible, in particular, to vary the speeds of the casings 7 and 7a, by acting on the speeds of the motors 1 and 1a, which could especially be electric motors with collectors (for direct current or alternating current).

It is also possible to vary the total quantity of liquid employed by limiting the travel of the scoops, while maintaining the same total mass of liquid. This total mass may, however, also be varied.

To this end, auxiliary fixed reservoirs may be employed which are not shown in Figs. l, 2 and 3. One of these is shown in Fig. 4. The liquid is passed by means of suitable pumps from this fixed reservoir to one of the rotary casings 7 and 7a when it is desired to increase the mass of the liquid.

On the other hand, if it is desired to reduce this mass, it is only necessary to set-up a derivation on the channels 17 and 17 so as to return the desired quantity of liquid into the fixed reservoir.

It should also be noted that in Fig. 1 no valve has been shown on the piping systems such as 17, whereas it is of course generally an advantage to provide such valves, since they give a supplementary means of regulation.

A further means of regulation (not shown) which may in some cases be very important, may be constituted by needles similar to those which are used for the regulation of hydraulic turbines and especially of Pelton wheels. These needles or spindles may be placed in particular inside the nozzles of the injectors.

The apparatus shown in Fig. 4 shows a device similar to that of Fig. 1 which has the special advantage of taking up less space in the longitudinal direction.

The casing 7a is in this case arranged around the casing 7, and in the example shown in Fig. 4 it is driven in rotation in the opposite direction to that of the casing 7. The casing 7 is rotatably driven by the driving shaft 38 by means of grooves 39. The shaft 38 passes through bearings 40 and 41 carried respectively by the support 5 and by the barrel v42 coupled to the support 5' by the arms 43. The support 5' is rigidly fixed to the deck 4 of the ship.

The shaft 38 is directly driven in rotation by the motor 1 which is mounted on the bracket 6 xed to the support 5'. A sleeve 44 (on the left-hand side of Fig. 4) is rigidly fixed to the casing 7a and enables it to be centered on the barrel 42-which serves as its bearing. The casing 7a carries in addition a ring 45 which is provided withintcrnal teeth 46. Y'

On the driving shaft 38, there is mounted besides on grooves 47, a pinion 48 provided with teeth 49. On

mounted wheels 51 provided with teeth 52 and 53 ofA different diameters. The teeth 52 of smaller diameter engage with the teeth 49 of the driving pinion 48. The teeth 53 engage with the internal teeth -47 which are rigidly fixed to the casing 7a.

,By this means, the casing 7a is driven in rotation by the motor 1 in the opposite direction to the casing 7, and the desired ratio of the angular speeds of the two casings is obtained by a suitable choice of the diameters of the four sets of teeth 49, 52, 53 and 46. In general, it is preferable in this way to make the linear speeds of the liquid rings in the casings 7 and 7'a equal or substantially equal in absolute value, but of opposite directions.

On the other hand, the casings 7 and 7a are supported by means of the sleeves 10 and 10a on the bearing sur faces 54 and 55 rigidly fixed to the frame 12.

The liquid-transfer devices are similar to those which have already been described with reference to Fig. l and operate in the same manner.

In Fig. 4, however, there has been shown in addition an auxiliary tank 56 which is not rotating but lixed. This tank rests on the frame 12. From this tank, four conduits pass out and rejoin the four transfer conduits formed in the frame. Two of these conduits, the conduits 57 and 57 only, are shown in Fig. 4. They are connected to the conduits 17 and 17 which serve to transfer the liquid from the casing 7 to the casing 7'a. A valve 5S enables the conduit 17 to be put into communication with the conduit 57 and interrupts the communication between the conduit 17 and the conduit 16. A valve 58 carries out the same function for the conduits 17' and 57'.

lf, for a certain period of time, the conduits 17 and 57 on the one hand and 17 and 57 on the other are put into communication, the liquid which is present in the casing 7 is sent during this period into the fixed tank 56 instead of being transferred to the casing 7 a. This enables the total quantity of liquid working in the apparatus to be reduced, if this is possible, that is to say if the condition of the sea can only give rise to a small or fairly small rolling motion.

If, on the contrary, it is desired to increase the quantity of liquid working (when it is necessary to counteract a greater degree of rolling) the two other conduits coming from the tank 56 (not shown in Fig. 4) are put into communication at the suitable moment with the injection conduits located in the casing 7 and, by virtue of suitable pumps (not shown in Fig. 4) the desired quantity of liquid passes from the tank 56 into the casing 7.

Use may also be made of the auxiliary fixed tank 56 if it is considered necessary to empty the two rotary casings 7 and 7,a, either before the apparatus is put into operation, or before it is stopped, with the object on the one hand of avoiding out-of-balance effects at the moment of starting or-of stopping, and on the other hand of reducing the inertia of the driven portions at these times.

In order to empty the liquid before stopping, use may be made of the scoops by proceeding as explained above for the case of a partial emptying. lf emptying has not been elected before stopping and it is desired to empty before starting-up again, use will be made of pumps (not shown on the drawing).

The uid employed under the conditions given above will in general be a liquid, its characteristics being varied according to the particular case of application. In particular, use can be made of liquids having very different densities and viscosities (for example oils, water, silicones, etc.). Use could also be made if so desired of liquids of high density (for example mercury) or even of powders (for example graphite powders, powdered bi-sulphide of molybdenum). In very many cases, it would appear desirable to give preference to a liquid of high fluidity.

Y Fig. 5 shows an apparatus embodying features of the present invention mounted in the hull of a ship to counterl act 1oscillations ofthe hull caused'by the sea surrounding the hull. The general geometrical axis of the apparatus 'is parallel to the longitudinal axis of thehull. As seen in Fig. 5, the supports 5, 5a and 12 are connected to the deck 4 of the ship. Upon these supports are mounted, as previously described, the apparatus assembly which includes the motors l and 1a, the rotary casings having the rims 8 and 8a, and the control box 26. In addition, a gyroscopic device 61 of known construction is mounted on a iplatform 60 which is secured to the hull. The gyropilot apparatus 61 acts upon, in known manner, the electrical contacts of the housing 62. These electrical contacts are connected to electrical conductors 63 and 64 which lead to the control box 26. In the box 26, these conductors are suitably connected to electric servo-motors which control pumps or distribution vanes. The conductors can also be connected to electro-magnets which suitably control distribution valves.

As has been already stated above, the invention is not limited to anti-rolling devices. It may in `particular be applied to counteract oscillations in various branches of industry, whether in the case of vehicles, of ships, of aircraft, or of fixed machines.

As far as the pitching of ships is concerned (in the cases in which it would be .possible to consider reducing them without disadvantage) the devices to be employed in accordance with the present invention would be exactly similar to those which have been described for counteracting rolling. The axes of rotation of the casings, in stead of being parallel to the rolling axis of the ship, would however be perpendicular to the longitudinal central plane.

The number and the arrangement of the apparatus such as those which have been described may be widely varied. For example, the rotary casings such as 7 and 7a may be arranged `otherwise than in the manner indicated; in particular they may be arranged side by side.

As regards the maintenance of the movement of the rotary casings, this may, as has been seen above, be effected by means of a single motor, with the interpositon of gears as in the case of Fig. 4. This maintenance may also be obtained by independent motors, as in the case of Fig. l. In this case, there may be an advantage in coupling together these two motors, electrically if they are electric motors.

It is very important to note that, broadly speaking, the assembly of nozzles formed by the piping systems such as 19 and 35 of Figs. 1, 2 and 3, forms the analogue of ya turbine rotor especially of a hydraulic turbine-which is assumed to be rigidly locked to the hull of the ship.

The apparatus according to the present invention essentially differs from the known devices, in which solid flywheels are used, with hydraulic means to periodically retard and accelerate the rotation velocity of the flywheels. In the present invention the liquid mass forms by itself the eliicient mass against the perturbing torque; moreover, the rotation velocity of the rotation maintaining member is substantially constant, for a given perturbing torque.

What I claim is:

l. In a structure exposed to oscillation forces, in combination, a frame rigid with said structure, an apparatus adapted to apply alternating mechanical impulses to said frame to counteract oscillations of said structure and comprising a liquid mass forming essentially an inertia mass, bearings connected to said frame, a first rotation maintaining member carried by said bearings and having a geometrical axis parallel to the axis of the oscillation to be counteracted and adapted to drive in rotation in a first direction at least a portion of said liquid mass at a substantially constant speed, second bearings connected to l said frame, a second rotation-maintaining member carried by said second bearings and having a geometrical axis adapted to drive in rotation the other portion of said liquid mass at a substantially constant speed, but in a direction of rotation opposite to said first direction, ,at Aleast on'e motor fixed on said frame and coupled with said rotationmaintaining members for driving them-in rotation, yreaction members connected to the frame and adapted to pass the liquid mass at appropriately selected instants from one of the rotation-maintaining members into the other rotation-maintaining member, and said reaction members being adapted to change the direction of flow of the liquid mass therein 'While substantially preserving the speed of said liquid mass at its absolute value.

2. In a structure exposed to oscillation forces, in cornbination, a frame rigid with said structure, an apparatus adapted to apply alternating mechanical impulses to said frame to counteract oscillations of said structure and comprising a liquid mass forming essentially an inertia mass, bearings connected to said frame, a first rotation-maintaining member carried by said bearings and having `a geometrical axis parallel to the axis of the oscillation to be counteracted and adapted to drive in rotation in a first directiony at least a portion of said liquid mass at a substantially constant speed, second bearings connected to said frame, a second rotation-maintaining member carried by said second bearings and having a geometrical axis parallel to the geometrical axis of the first rotationmaintaining member and adapted to drive in rotation the other portion of said liquid mass at a substantially constant speed but in a direction of rotation opposite to saidvfirst direction, at least one motor fixed on said frame and coupled with said rotation-maintaining members for driving them in rotation, a first group of reaction devices connected to said frame and comprising (a) extraction devices adapted to extract the liquid at appropriately selected instants from the first rotation-maintaining member, (b) injection devices adapted to return the liquid into the second rotation-maintaining member and (c) reaction conduits serving to connect together said extraction devices and said injectiondevices and constructed to force the streams of liquid to change direction before the liquid is returned to the second rotation-maintaining member, a second group of reaction devices connected to said frame and comprising (a) extraction devices adapted to draw the liquid at appropriately selected instants from the seoond rotation-maintaining member, (b) injection devices adapted to re-inject the liquid into the first rotation-maintaining member and (c) reaction conduits serving to connect together said extraction devices and said injection devices and constructed to force the streams `0f liquid again to change direction before the liquid is re-injected into the first rotation-maintaining member.

3. An apparatus as defined in claim l, in which said rotation-maintaining members are rotating casings.

4. In a ship exposed to rollingoscillations, in combination, a hull and a deck rigid with said hull, an apparatus adapted to apply alternating mechanical impulses to said deck to counteract rolling oscillations of said ship forming and comprising a liquid mass, essentially an inertia mass, bearings connected to the deck, a first rotation-maintaining member carried by said bearings and having a geometrical axis parallel to the rolling axis of the ship and adapted to drive in rotation in a first direction at least a portion of said liquid mass at a substantially constant speed, second bearings connected to said deck, a second rotation-maintaining member carried by said second bearings adapted to drive in rotation the other portion of saidV liquid mass at a substantially constant speed but in a direction of rotation opposite to said rst direction, at least one motor fixed on said deck and coupled with said rotation-maintaining members for driving them in rotation, a first group of reaction devices connected to the deck and comprising (a) extraction devices adapted to extract the liquid at appropriately selected instants from the first rotation-maintaining member, (b) injection devices adapted to return the liquid into the second rotation maintaining member, and (c) reaction conduits serving to connect together said extraction devices and said injection devices and Constructed to force the streams of liquid to change direction before the liquid is returnedv to the second rotation-maintaining member, a second group of reaction devices connected to said deck and comprising (a) extraction devices adapted to draw the liquid at appropriately selected instants from the second rotationmaintaining member, (b) injection devices adapted to reinject the liquid into the first rotation-maintaining member, and (c) reaction conduits serving to connect together said extraction devices and said injection devices and constructed to force the streams of liquid again to change direction before the liquid is' re-injected into the iirst rotation-maintaining member.

5. An apparatus as dened in claim 2, wherein the extraction devices adapted to extract the liquid at appropriately selected instants from the rotation-maintaining members comprise draining members secured against rotation but movable radially, and scoops fixed at the ends of said draining members.

6. An apparatus as dened in claim 2, wherein the injection devices compriseconduits secured against rotation but movable radially, and injectors fixed at the ends of said conduits.

7. In a ship exposed to oscillation lforces, in combination, a hull and a deck rigid with said hull, an apparatus adapted to apply alternating mechanical impulses to said deck to counteract oscillations of said ship and comprising a liquid mass forming essentially an inertia mass, bearings connected to the deck, a rst rotation-maintaining member carried by said bearings and having a geometrical axis parallel to the axis of the oscillation to be counteracted and adapted to drive in rotation in a first direction at least a portion of said liquid mass at a substantially constant speed, second bearings connected to said deck, a second rotation-maintaining member carried by said second bearings adapted to drive in rotation the other portion of said liquid mass at a substantially constant speed, but in a direction of rotation opposite to said first direction, at least one motor xed on said deck and coupled with said rotation-maintaining members for driving them in rotation, reaction members connected to the deck and adapted to pass the liquid mass at appropriately selected instants from one of the rotation-maintaining members into the 12 other rotation-maintaining member, said reaction members being adapted to change the direction of flow ofthe liquid mass therein while substantially preserving the speed of said liquid mass at its absolute value.

8. In a ship exposed to rolling oscillations, in combination, a hull and a deck rigid with said hull, an apparatus adapted to apply alternating mechanical impulses to said deck to counteract rolling oscillations of said ship and comprising a liquid mass forming essentially an inertia mass, bearings connected to the deck, a first rotation-maintaining member carried by said bearings and having a geometrical axis parallel to the rolling axis of the ship and adapted to drive in rotation in a first direction at least a portion of said liquid mass at a substantially constant speed, second bearings connected to said deck, a second rotation-maintaining member carried by said second bearings and having a geometrical axis parallel to the geometrical axis of the first rotation-maintaining member and adapted to drive in rotation the other portion of said liquid mass at a substantially constant speed but in a direction of rotation opposite to said first direction, at least one motor fixed on said deck and coupled with said rotation-maintaining members for driving them in rotation, reaction members connected to the deck and adapted to pass the liquid mass at appropriately selected instants from one of the rotation-maintaining members into the other rotation-maintaining member, said reaction members being adapted to change the direction of ow of the liquid mass therein while substantially preserving the speed of said liquid mass at its absolute value.

9. An apparatus as defined in claim 5, further comprising hydraulic means for controlling the movable parts of the extraction devices.

10. An apparatus as defined in claim 6, further comprising hydraulic means for controlling the movable parts of the injection devices.

References Cited in the tile of this patent UNITED STATES PATENTS 1,571,264 Gretsch Feb. 2, 1926 2,017,072 Minorsky Oct. 15, 1935 2,338,147 Von Den Steinen Jan. 4, 1944 

